function select() {
    let select = document.getElementById("s1");
    let options = select.options;
    let index = select.selectedIndex;
    let selectedText = options[index].value;
    var quan2= document.getElementById("quan2");
    console.log(selectedText)
    if(selectedText==1){
        quan2.style.display='block'
    }else {
        quan2.style.display='none'
    }
}